compile ‘org.springframework.boot:spring-boot-starter-thymeleaf‘
compile ‘io.ratpack:ratpack-thymeleaf:1.4.2‘

import me.ele.api.portal.api.dto.ApiPortalOperator;
import me.ele.elog.Log;
import me.ele.elog.LogFactory;
import org.apache.commons.lang3.StringUtils;
import org.springframework.beans.BeanUtils;
 
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.mail.javamail.JavaMailSender;
import org.springframework.mail.javamail.MimeMessageHelper;
import org.springframework.mail.javamail.MimeMessagePreparator;
import org.springframework.stereotype.Service;
import
 
 org.thymeleaf.TemplateEngine;
import org.thymeleaf.context.WebContext;
import ratpack.thymeleaf.internal.ThymeleafHttpServletRequestAdapter;
import ratpack.thymeleaf.internal.ThymeleafHttpServletResponseAdapter;
import ratpack.thymeleaf.internal.ThymeleafServletContextAdapter;

import javax.mail.internet.InternetAddress;
 
import javax.mail.internet.MimeMessage;
import javax.servlet.ServletContext;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.beans.PropertyDescriptor;
import java.lang.reflect.Method;
import java.util.*;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.FutureTask;

/**
 * Created by hujunzheng on 17/9/8.
 */
@Service
public class MailService {

    @Autowired
    private MailProperties mailProperties;

    @Autowired
    private JavaMailSender javaMailSender;

    @Autowired
    private TemplateEngine templateEngine;

    private static final Log log = LogFactory.getLog(MailService.class);
    /**
     * 發送郵件
     * @param userEmail
     * @param templateId
     */
    public void sendMail(String userEmail, Map<String, Object> params, int templateId) {
        sendMailMultiParams(new String[] {userEmail}, params, templateId);
    }

    public void sendMail(String userEmail, Object obj, int templateId) {
        Map<String, Object> params = objectToMap(obj);
        sendMailMultiParams(new String[] {userEmail}, params, templateId);
    }

    public void sendMail(String userEmail, String  message, String subject) {
        sendSampleMail(new String[] {userEmail}, message, subject);
    }

    public void sendMail(String[] userEmails, Map<String, Object> params, int templateId) {
        sendMailMultiParams(userEmails, params, templateId);
    }

    public void sendMail(String[] userEmails, Object obj, int templateId) {
        Map<String, Object> params = objectToMap(obj);
        sendMailMultiParams(userEmails, params, templateId);
    }

    public void sendMail(String[] userEmails, String  message, String subject) {
        sendSampleMail(userEmails, message, subject);
    }

    private Map<String, Object> objectToMap(Object obj) {
        PropertyDescriptor[] propertyDescriptors = BeanUtils.getPropertyDescriptors(obj.getClass());
        Map<String, Object> params = new HashMap<>();
        for (PropertyDescriptor property : propertyDescriptors) {
            String key = property.getName();
            if (key.compareToIgnoreCase("class") == 0) {
                continue;
            }
            Optional<Method> getter = Optional.ofNullable(property.getReadMethod());
            try {
                Object value = getter.isPresent() ? getter.get().invoke(obj) : null;
                params.put(key, value);
            } catch (ReflectiveOperationException e) {
                e.printStackTrace();
            }
        }
        return params;
    }

    /**
     * 異步 分別發送 發送郵件
    * */
    public List<String> asynSendMails(List<ApiPortalOperator> apiPortalOperators, Object bodyParams) {
        ExecutorService executorService = Executors.newFixedThreadPool(10);
        List<FutureTask<String>> futureTasks = new ArrayList<>();
        for (ApiPortalOperator apiPortalOperator : apiPortalOperators) {
            FutureTask<String> futureTask = new FutureTask(() -> {
                try {
                    this.sendMail(apiPortalOperator.getEmail(), bodyParams, 1);
                } catch (Exception e) {
                    return "郵件to " + apiPortalOperator.getEmail() + " 發送異常：" + e.getMessage();
                }
                return "郵件to " + apiPortalOperator.getEmail() + " 發送成功";
            });
            futureTasks.add(futureTask);
            executorService.submit(futureTask);
        }

        List<String> result = new ArrayList<>();
        for (int i=0; i<futureTasks.size(); ++i) {
            FutureTask futureTask = futureTasks.get(i);
            try {
                result.add((String) futureTask.get());
            } catch (Exception e) {
                result.add("to " + apiPortalOperators.get(i).getEmail() + " 發送失敗：" + e.getMessage());
            }
        }

        return result;
    }

    /**
     * 異步 多個收件人一起 發送郵件
     * */
    public String asynSendMail(List<ApiPortalOperator> apiPortalOperators, Object bodyParams) {
        ExecutorService executorService = Executors.newSingleThreadExecutor();
        String[] userEmails = apiPortalOperators.stream().map(ApiPortalOperator::getEmail).toArray(String[]::new);
        FutureTask<String> futureTask = new FutureTask(() -> {
            try {

                this.sendMail(userEmails, bodyParams, 1);
            } catch (Exception e) {
                return "郵件to " + StringUtils.join(userEmails, ‘,‘) + " 發送異常：" + e.getMessage();
            }
            return "郵件to " + StringUtils.join(userEmails, ‘,‘) + " 發送成功";
        });
        executorService.submit(futureTask);
        try {
            return futureTask.get();
        } catch (Exception e) {
            e.printStackTrace();
            return "郵件to " + StringUtils.join(userEmails, ‘,‘) + " 發送異常：" + e.getMessage();
        }
    }

    private void sendSampleMail(String[] userEmail, String msg, String subject) {
        MimeMessagePreparator preparator = new MimeMessagePreparator() {
            @Override
            public void prepare(MimeMessage mimeMessage) throws Exception {
                MimeMessageHelper message = new MimeMessageHelper(mimeMessage, "utf-8");
                message.setTo(userEmail);
                message.setFrom(new InternetAddress(mailProperties.getFrom()));
                message.setSubject(subject);
                message.setText(msg);
            }
        };
        try {
            this.javaMailSender.send(preparator);
        } catch (Exception ex) {
            log.error("Mailing Exception! user email is: {}", userEmail, ex);
        }
        log.info("Mail sent successfully, user email is: {}", userEmail);
    }

    private String buildTemplateMessage(String templateName, Map<String, Object> messages) {
        HttpServletRequest request = new ThymeleafHttpServletRequestAdapter();
        HttpServletResponse response = new ThymeleafHttpServletResponseAdapter();
        ServletContext servletContext = new ThymeleafServletContextAdapter();
        WebContext context = new WebContext(request, response, servletContext);
        context.setVariables(messages);
        return templateEngine.process(templateName, context);
    }

    /**
     * 當發郵件時有多個不定參數時
     * @param userEmail 用戶郵箱
     * @param params 發郵件的參數
     * @param templateId
     */
    private void sendMailMultiParams(String[] userEmail, Map<String, Object> params, Integer templateId) {

        String templateName = MailTemplate.getTemplateName(templateId);

        MimeMessagePreparator preparator = new MimeMessagePreparator() {
            @Override
            public void prepare(MimeMessage mimeMessage) throws Exception {
                MimeMessageHelper message = new MimeMessageHelper(mimeMessage, "utf-8");
                message.setTo(userEmail);
                message.setFrom(new InternetAddress(mailProperties.getFrom()));
                message.setSubject(MailTemplate.getTemplateSubject(templateId));

                String content = buildTemplateMessage(templateName, params);
                System.out.println(content);
                message.setText(content, true);
            }
        };
        try {
            this.javaMailSender.send(preparator);
        } catch (Exception ex) {
            log.error("Mailing Exception! user email is: {}, template params are: {}, template_id is: {}", userEmail, params.toString(), templateId, ex);
        }
        log.info("Mail sent successfully, user email is: {}, template params: {}, template_id is: {}", userEmail, params.toString(), templateId);
    }
}

Thymeleaf 中有 plain context （不支持對url參數的解析）和 web context（支持對url參數的解析）

We‘ll have to change our code to create a web context, instead of a plain context. Change will be here: 

參考：https://github.com/ratpack/ratpack/blob/master/ratpack-thymeleaf/src/main/java/ratpack/thymeleaf/Template.java#L69-69

The IWebContext interface seems coupled to the servlet API, but after quick look at the code I don‘t think this will be a problem. I think we can just provide null values for things like request/session etc. that we can‘t provide. If that turns out to be a problem… we can look at providing implementations of those Servlet API type in so far makes sense.

springboot mail+Thymeleaf模板